The present invention relates to flexible coupling devices for shafts to permit and facilitate transmission of torque between a drive and a driven shaft while accommodating misalignment between the shafts. More particularly, the present invention relates to a spool type flexible coupling where the spool may be split so as to enable the coupling to be established between the respective shafts with a greater degree of accommodation of distance variation between the shafts to be coupled and particularly where the shafts"" ends are closely spaced and cannot be readily moved.
In the field of flexible couplings, a number of considerations affecting the design of a flexible coupling exist. Among these are the degree of misalignment tolerated, the anticipated torque loads and design constraints relating to the installation allowed. In a number of flexible couplings of the prior art, installation of the coupling has been difficult due to the substantially static character of the coupling members. In other arrangements, only a limited type of elastomeric material could be employed in a coupling to accommodate the torque loads desired. In still other arrangements, the cost of the coupling has been increased, as a result of the complicated design of the flexible elements of the coupling such as is often required in pre-existing power shaft installations. In order to provide simplified structures for the flexible elements of the coupling, the prior art has often relied upon a variation in another portion of the installed coupling elements. This has often resulted in increased weight of the coupling which is undesirable in terms of the efficient transfer of torque from a power source to a driven member.
Where the connection flanges of the shafts to be coupled are a significant distance apart, assembly is in general much easier to accomplish than where the shafts are close together. Accordingly, where adequate spacing was provided, the prior art has generally resorted to the use of metal coupling elements in order to reliably transmit torque over a range of operating speeds and loads. In general, elastomeric materials have been avoided and this has complicated the installation procedure as well as increased the cost of such couplings. For closely spaced shafts, however, the use of elastomeric elements has become a necessity due to the confined space available to install and operate the coupling.
The present invention avoids the complications of the prior art devices yet provides a flexible coupling, which, in its basic form, accommodates a much broader range of distances between the shafts to be coupled from relatively distant to very closely located shafts yet reliably transmits torque over a satisfactory range and through an increased degree of tolerance for misalignment.
In one form of the invention, the coupling spool is split longitudinally and reinforced during assembly by a rigid ring which may be bolted in place during installation. The rigid ring will serve as reinforcement for the split spool and will facilitate installation in positions that would be otherwise difficult or expensive to attempt. In addition, a flexible elastomeric ring may is employed as the flexing member of the coupling and may also be split or formed in arcuate sections and installed on the respective halves of the split spool prior to installation in the coupling. This will also facilitate assembly with closely spaced shafts.
In another form, the present invention provides a coupling spool on which are initially movably mounted two coupling sleeves at opposite ends thereof. Each coupling sleeve is provided with a flexible diaphragm in the form of an elastomeric ring which can be coupled directly to a flange of a coupling hub which in turn is mounted on a drive or a driven shaft. The flexible rings are spaced apart a distance that is typically more substantial than in the prior art arrangements. Minor manufacturing changes will enable the coupling of this form of the present invention to accommodate a broad range of distances between the shafts to be coupled. The material of the coupling spool and associated sleeves will be such that these members can be readily adhered together by adhesive binding, riveting or the like. As noted above, the flexible rings carried by the coupling sleeves are preferably made from a flexible elastomeric material that is shaped to accommodate the degree of flexibility needed for a particular application without experiencing sheer stresses or tearing of this material in normal use. With the flexible ring preferably manufactured in an annular shape, a taper is provided where the ring narrows as one moves radially outwardly from the inner periphery of the ring to adjacent the outer rim which is narrower in axial extent. The ring is made by either compression or injection molding to achieve the desired cross-sectional shapes.
With the flexible couplings of the present invention, a user a will be able to transmit high torque loads while accommodating high degrees of misalignment. Further, the coupling is characterized by ease of installation in either narrow or extended spaces between the shafts and by a low number of individual parts for assembly. With even widely spaced apart shafts, the flexible coupling of this invention will provide high-speed capability due to the high radial rigidity of the flexible elements.
The foregoing and other advantages will become apparent as consideration is given to the following detailed description taken in conjunction with the accompanying drawings, in which: